Noroviruses, infamous for causing outbreaks of gastroenteritis on cruise ships, may now be recognized as a common cause of travelers' diarrhea in multiple regions of the world as well. Researchers from the U.S. and abroad detail their findings in the May 2010 issue of the Journal of Clinical Microbiology.

Travelers' diarrhea occurs frequently in people traveling between industrialized nations and regions of the developing world. Currently, travelers' diarrhea is largely attributed to E. coli infection, however, a specific causatory agent is never identified in up to 40% of reported cases. Such incidents of unexplained diarrheal illness are believed to be caused by undetected bacterial or nonbacterial pathogens and until now the prevalence of noroviruses as a cause of diarrhea in international travelers has not been well known.

Noroviruses, which are contracted through fecal-oral transmission, are highly contagious in people of all ages. Samples from international travelers to Mexico, Guatemala, and India suffering from diarrhea were collected and examined for the prevalence of noroviruses. Of the 571 samples studied noroviruses were identified in 10.2% of cases, making it second to only diarrheagenic Escherichia coli as the most common pathogen associated with the travelers' diarrhea.

"This study demonstrates that noroviruses are an important pathogen of travelers' diarrhea in multiple regions of the world," say the researchers. "It is likely that this enteric pathogen has long been underestimated as a cause of travelers' diarrhea due to limitations of detection methods."